<html>
  <head>
    <script src="/dist/ffmpeg.dev.js"></script>
    <style>
      html, body {
        margin: 0;
        width: 100%;
        height: 100%
      }
      body {
        display: flex;
        flex-direction: column;
        align-items: center;
      }
    </style>
  </head>
  <body>
    <h3>Upload a mp4 (x264) video and trim its first 1 seconds and play!</h3>
    <video id="output-video" controls></video><br/>
    <input type="file" id="uploader">
    <p id="message"></p>
    <script>
      const { createFFmpeg, fetchFile } = FFmpeg;
      const ffmpeg = createFFmpeg({ log: true });

      const trim = async ({ target: { files } }) => {
        const message = document.getElementById('message');
        const { name } = files[0];
        message.innerHTML = 'Loading ffmpeg-core.js';
        await ffmpeg.load();
        message.innerHTML = 'Start trimming';
        ffmpeg.FS('writeFile', name, await fetchFile(files[0]));
        await ffmpeg.run('-i', name, '-ss', '0', '-to', '1', 'output.mp4');
        message.innerHTML = 'Complete trimming';
        const data = ffmpeg.FS('readFile', 'output.mp4');

        const video = document.getElementById('output-video');
        video.src = URL.createObjectURL(new Blob([data.buffer], { type: 'video/mp4' }));
      }
      const elm = document.getElementById('uploader');
      elm.addEventListener('change', trim);
    </script>
  </body>
</html>
